1. Field of the Invention
The present invention relates to a device for absorption of impact energy on an automobile, with at least one energy absorber arranged between a bumper and the vehicle chassis. More particularly, the invention relates to devices of this type, wherein the energy absorber has a deformation element which deforms in the event of a collision, whereby the energy imparted on the vehicle during the collision is at least partially converted by the deformation into deformation work.
2. Description of the Related Art
Several different solutions are already known for transferring kinetic energy generated during a collision of a vehicle to chassis via the bumper. More particularly, energy absorption systems are generally differentiated in that the elements change reversibly or an irreversibly during impact. The first category includes, for example, systems which dissipate the kinetic energy transferred to to the vehicle via the bumper by hydraulic damping elements. However, such systems are relatively expensive and tend to require installation space which is unavailable in many typical applications. Disadvantageous is also the relatively high weight of such systems. For this reason, absorption systems with hydraulic damping elements are typically not used in vehicles for the European mass market, in particular not in passenger vehicles.
Absorber systems with reversibly changing elements are therefore typically used in passenger vehicles. Some conventional systems use as energy absorbers crash boxes or so-called impact absorbers between the bumper and the vehicle chassis. Such absorbers include a deformation element which deforms on impact and dissipates the generated kinetic energy by conversion into deformation work. A bumper system with a energy absorber of this type is known, for example, from DE 102 434 60 A1. Problematic with this and comparable systems is, for example, that the absorption characteristic is the same, regardless if a vehicle equipped in this manner collides with another vehicle, a stationary obstacle, or with a pedestrian. Pedestrians can therefore be seriously injured in such situations. The automotive industry and suppliers have therefore attempted since some time to reduce the risk of injury to pedestrians by appropriate design measures.
For example, DE 101 59 864 A1 discloses a solution, wherein sensors determine the most likely type of an impending collision. As described in this published patent application, in the event of a collision with a pedestrian, the end of the front hood facing the windshield is slightly raised by corresponding actuators arranged on the vehicle, and a crossbeam arranged below the bumper is displaced in the direction of travel. The object of this measure is to avoid running over the pedestrian and to make possible for the body of the pedestrian to roll across the vehicle. Nevertheless, the solution is hardly suitable to prevent fractures in the lower leg, because these are auxiliary measures which are less intended to affect the manner in which the impact energy is dissipated, but rather attempt to remove the body of an affected pedestrian from the immediate danger zone on a predetermined trajectory in the event of an impact. However, the impact energy has then already affected the knee or the lower leg of the pedestrian.